The invention relates to a process for the automatic calibration of a high-resolution electronic balance, in which the changes in the parameters affecting the weighing system are detected and processed by the evaluation circuit of the weighing system and/or a microprocessor.
In high resolution balances, changes in temperature, air pressure, aging of the components, etc., affect the balance so that the indicated weight is not correct. A periodic recalibration of the balance therefore is absolutely necessary.
Error compensation processes for electronic high-resolution balances are known. From DE-A1-31 06 534 it is known to detect the current air pressure and continuously to take the detected value into consideration in the electronic evaluation of weight.
In CH-PS 624 773, correction values for several components which can affect the measurement result are detected and recorded. Moreover, temperature coefficients and changes in values caused by age are detected and taken into consideration by the computer in the calculation of the final measurement result.
These known error compensation processes use changes in values of the factors affecting the measurement result for continuous correction of the measurement result. In particular a calibrating factor is determined which corrects the weighing results so that the indicated weight agrees with the laid on weight.
Another known process described in EP-A1-0 044 707 comprises an automatic recalibration which is triggered after a specific time has passed or a given number of weighings have been made or after each taring. Such a rigid recalibration rule results in recalibration being performed when objectively it would not be necessary, and thus constitutes an often unnecessary disturbance during a series of weighings.
A disadvantage of these compensation processes is that they tend to be made without regard for the need for recalibration or its efficacy.